Google's quantum computer flunks landmark speed test

THE quantum revolution is still in the slow lane. The first head-to-head speed test of the D-Wave Two, the commercial quantum computer recently purchased by Google, suggests that the machine performs no better than an ordinary PC.

In theory, quantum computers are capable of calculating answers to problems much faster than standard PCs. Instead of storing information in bits as either 0s or 1s, quantum machines use quantum bits, or qubits, that can be both 0 and 1 at the same time. So far, however, the quantum devices built in labs can only support a handful of qubits, which limits their speed.

The computers built by commercial firm D-Wave of Burnaby in British Columbia, Canada, have many more qubits – about 500 – but use a method known as adiabatic quantum computing, which, unlike the traditional method, has not yet been proved to give a quantum power boost. Nevertheless, Google splashed out on a D-Wave Two machine last year. It is housed at a NASA research centre. The company has so far used it to design blink-detection algorithms for its upcoming Glass headset and NASA is exploring its potential for finding exoplanets.

Now a team led by Matthias Troyer of ETH Zurich in Switzerland has tested a D-Wave Two computer against a conventional machine running an optimised algorithm – and found no evidence of superior performance in the quantum device.

Critics say the D-Wave computer is not exploiting quantum mechanics to calculate faster than a regular PC. But the latest test only looked at one specific type of problem, and Google is hopeful that the D-Wave Two will work faster in other areas.

D-Wave is also scheduled to release a new version of its quantum chip with 1000 qubits later this year. The company thinks that will improve benchmark results. "We haven't yet seen any fundamental limits to performance that can't be improved with design changes," says Jeremy Hilton of D-Wave.

This article appeared in print under the headline "Quantum chip flunks landmark speed test"

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